Definitions
First fall freeze - The first day, after July 15, that the temperature reached or fell below 0.0°C.
Last spring freeze - The last day, on or before July 15, that the temperature reached or fell below 0.0°C.
Growing season - Defined as the number of days between the last spring freeze and the first fall freeze (exclusive).
Thunderstorm day - A day with a thunderstorm reported - a day being defined as 06Z to 06Z.
Severe thunderstorm - A thunderstorm producing one of: hail nickel sized or larger, gusts at least 90 km/h, 50 mm in an hour, or tornado.
Degree days - The number of days above or below a certain threshold (for example, the number of 30°C days is defined as the number of days with a maximum temperature of 30.0°C or higher).
Measurable precip - Rain, snow and precipitation are considered 'measurable' at or above 0.2 (mm or cm).
Trace - Rain, snow, precipitation or snow depth that is not measurable. Note that some automatic precipitation sensors can report 0.1 mm due to greater precision (such as is the case with Winnipeg A CS (XWG) starting in November 2020).
Winter snow pack - The longest lasting snow pack of the winter season (either consistently 2 cm depth or more, or trace depth or more).
Spring melt date - The date when the predominant winter snow pack(s) has/have completely melted (either to 1 cm or less or to 0 cm).
Fall initiation date of snow pack - The date when the winter snow pack began (either 2 cm depth or more or trace depth or more).
For humidex and wind chill records, only wind chill at or below zero (0.0) and humidex at or above 20.0 are considered.
Thunderstorm off-season is the longest period without a thunderstorm in the cold season. Thunderstorm season is the period between the first and last thunderstorms of the season – the first denoting the end of the off-season and the start of the new season - the last denoting the start of the off-season and the end of the thunderstorm season.
Last spring freeze - The last day, on or before July 15, that the temperature reached or fell below 0.0°C.
Growing season - Defined as the number of days between the last spring freeze and the first fall freeze (exclusive).
Thunderstorm day - A day with a thunderstorm reported - a day being defined as 06Z to 06Z.
Severe thunderstorm - A thunderstorm producing one of: hail nickel sized or larger, gusts at least 90 km/h, 50 mm in an hour, or tornado.
Degree days - The number of days above or below a certain threshold (for example, the number of 30°C days is defined as the number of days with a maximum temperature of 30.0°C or higher).
Measurable precip - Rain, snow and precipitation are considered 'measurable' at or above 0.2 (mm or cm).
Trace - Rain, snow, precipitation or snow depth that is not measurable. Note that some automatic precipitation sensors can report 0.1 mm due to greater precision (such as is the case with Winnipeg A CS (XWG) starting in November 2020).
Winter snow pack - The longest lasting snow pack of the winter season (either consistently 2 cm depth or more, or trace depth or more).
Spring melt date - The date when the predominant winter snow pack(s) has/have completely melted (either to 1 cm or less or to 0 cm).
Fall initiation date of snow pack - The date when the winter snow pack began (either 2 cm depth or more or trace depth or more).
For humidex and wind chill records, only wind chill at or below zero (0.0) and humidex at or above 20.0 are considered.
Thunderstorm off-season is the longest period without a thunderstorm in the cold season. Thunderstorm season is the period between the first and last thunderstorms of the season – the first denoting the end of the off-season and the start of the new season - the last denoting the start of the off-season and the end of the thunderstorm season.
